The Tissue Analysis Core will provide the Program Project with histological and immunohistochemical analysis of cells grown in culture, explants grown as xenografts in athymic mice, and human tumor specimens which will be analysis for markers uncovered during laboratory investigations. We view the analysis of the signal transduction cascade in clinical human specimens as the ultimate test of the discoveries made in the cell culture and xenograft systems. The use of human specimens by members of the specific projects has already occurred and continues. Dr. Frierson will use his immunohistochemical expertise to interpret antibody staining in cell culture, experimental animal, and clinical human prostate cancer specimens.